When the oil pressure drops below ~30 PSI, the oil squirters that cool the bottom of the pistons turn off. If that happens under load (it is fine at idle), that is a huge amount of heat into the pistons with no cooling, and you risk melting/cracking them. I would be concerned any time the oil pressure drops below about 35 under load, personally. Adding an oil cooler will help with that.
The P0087 is from a low rail pressure, and indicates there is a problem with the fuel system where it can't provide all the fuel it needs. This is probably the limp they are feeling. Adding a lift pump might solve this one, or you could identify if the injector(s) and/or CP3 are the weak link and replace them as needed. I would personally start with a lift pump. And an oil cooler.
The P0674 is a glow plug code. Figure out which glow plug(s) are bad and replace them, that's an easy job. If I read it right, that code says cylinder #4, which is one back from the front on the driver's side of the motor.
The P0087 is from a low rail pressure, and indicates there is a problem with the fuel system where it can't provide all the fuel it needs. This is probably the limp they are feeling. Adding a lift pump might solve this one, or you could identify if the injector(s) and/or CP3 are the weak link and replace them as needed. I would personally start with a lift pump. And an oil cooler.
The P0674 is a glow plug code. Figure out which glow plug(s) are bad and replace them, that's an easy job. If I read it right, that code says cylinder #4, which is one back from the front on the driver's side of the motor.
